This is a package deal that includes (2) Skar Audio SDR-8 D4 8-inch car subwoofers. The Skar Audio SDR series was engineered to dish out reliable, hard hitting, and low spectrum sound. Featuring a high flux ferrite motor, This woofer will provide extreme power handling for extended periods of time. The SDR series will quickly become a customer favorite, as it's perfect for people just entering the world of car audio all the way up to seasoned pros. The SDR-8 D4 features a 2" High temperature high temperature copper voice coil that is attached to our Skar Audio signature red spider. The surround on the SDR series is a high roll foam surround which allows the woofer to produce riveting low end bass response. The SDR-8 D4 subwoofer has a max power rating of 700 watts and a RMS power rating of 350 watts per subwoofer. Recommended sealed box Volume: 0.55 ~ 0.75 ft³, recommended ported Box Volume: 0.75 ~ 1.00 ft³. Frequency response: 30 - 350 Hz, Sensitivity: 83.7 dB, Fs: 39 Hz. Subwoofer Mounting Depth: 4.5625", total height: 5.5", outside diameter: 8.5", cut-out diameter: 7.1".